Yellow-feathered Chickens Research Articles

Derivation and characterization of primordial germ cells from Guangxi yellow-feather chickens

The Guangxi yellow-feather chicken is a very important breed used as a broiler in southern China, but the pure line is being threatened by continual introduction of foreign genetics into its breeding program to make it more marketable. In the current study, we isolated primordial germ cells (PGCs), a cell type committed to form sperm or eggs and that is responsible for passing genetic material from one generation to the next, from Guangxi yellow-feather chickens and cultured them in a cell-insert system. Three stable cell lines, all male, were established from 10 isolations. These cells proliferated and expressed germ cell-related markers such as SSEA-1 and EMA-1 after prolonged culture in vitro. After genetic modification, these PGCs retained significant potential to colonize the gonads and give rise to gametes when they were reintroduced into the vasculature of stage-15 HH embryos, confirming their germline cell characteristics. The ability to culture PGCs and preserve the genetics from this species would not only be of significant importance for biodiversity conservation, but also holds promise for use of these cells in breeding strategies in the future.

Evaluation of the spoilage potential of bacteria isolated from chilled chicken in vitro and in situ

Microorganisms play an important role in the spoilage of chilled chicken. In this study, a total of 53 isolates, belonging to 7 species of 3 genera, were isolated using a selective medium based on the capacity to spoil chicken juice. Four isolates, namely Aeromonas salmonicida 35, Pseudomonas fluorescens H5, Pseudomonas fragi H8 and Serratia liquefaciens 17, were further characterized to assess their proteolytic activities in vitro using meat protein extracts and to evaluate their spoilage potential in situ. The in vitro studies showed that A. salmonicida 35 displayed the strongest proteolytic activity against both sarcoplasmic and myofibrillar proteins. However, the major spoilage isolate in situ was P. fragi H8, which exhibited a fast growth rate, slime formation and increased pH and total volatile basic nitrogen (TVBN) on chicken breast fillets. The relative amounts of volatile organic compounds (VOCs) originating from the microorganisms, including alcohols, aldehydes, ketones and several sulfur compounds, increased during storage. In sum, this study demonstrated the characteristics of 4 potential spoilage bacteria on chilled yellow-feather chicken and provides a simple and convenient method to assess spoilage bacteria during quality management.

Near-Freezing Temperature Storage (−2C) for Extension of Shelf Life of Chilled Yellow-Feather Broiler Meat: A Special Breed in Asia

As a special breed in Asia, yellow-feather broilers have high nutrition and can deteriorate easily under chilled conditions. The present work evaluated the effect of different storage temperatures (−2, 1 and 4C) on the shelf life of chilled yellow-feather chicken under modified atmosphere packaging (CO2/N2: 80%/20%). The total viable counts reached the limit value (7.0 log colony-forming unit [cfu]/g) after 28 and 12 days of storage at 1 and 4C, whereas it did not exceed 7.0 log cfu/g during the whole −2C storage period. The samples stored at −2C had the lowest total volatile basic nitrogen content and maintained the best sensory quality and lowest drip loss among the three groups. The shelf lives of samples stored at −2 and 1C were significantly extended for 16 days compared with traditional chilling at 4C. Our results provide practical information on shelf life extension of chilled yellow-feather broiler meat, which provide benefits to the industry to reduce unnecessary food waste. Practical Applications As a special species in Asia, yellow-feather broiler meat has more distinctive flavor, and is thereby favored by consumers. As a result of rapid deterioration, it is imperative to develop a novel preservation technology for chilled yellow-feather chicken. In this work, we determined the quality changes of the shelf life of chilled yellow-feather chicken half-carcass with high CO2-modified atmosphere packaging stored at −2, 1 and 4C. The shelf lives of samples stored at −2 and 1C were significantly extended for 16 days compared with traditional chilling at 4C. Our results will provide practical information to extend the shelf life of chilled yellow-feather broiler meat, which will be of benefit to the poultry industry to reduce unnecessary food waste.

High CO2-modified atmosphere packaging for extension of shelf-life of chilled yellow-feather broiler meat: A special breed in Asia

This work evaluated the effect of air- and modified atmosphere-packaging (MAP) on the shelf life of chilled yellow-feather chicken, which is a special breed in China. Fresh half-carcasses were stored in air and under modified atmosphere packaging (M-H: 80% CO2/20% N2 and M-L: 30% CO2/70% N2) at 4 °C for up to 12 days. Microbiological, physico-chemical and sensory attributes were measured. The results showed that total viable counts (TVC) reached the limiting value (7.0 log CFU/g) after 4, 10 and 8 days of storage under aerobic, M-H packaging and M-L packaging conditions, respectively, while the sensory values (odor and surface slime data) and the percentage of drip loss were in good agreement with the trend for TVC. During the storage, the total volatile basic nitrogen (TVB-N) content of broiler meat in MAP packaging was lower than that in air-packaging, however, the M-H group had the highest storage losses. In conclusion, high CO2 (80%) concentration packaging prolonged the shelf-life by at least 6 days when stored at 4°C. Our results provide practical information to extend the shelf-life of chilled yellow-feather broiler meat, which will benefit the poultry industry by reducing unnecessary waste.

Effects of fermented cottonseed meal on the growth performance, apparent digestibility, carcass traits, and meat composition in yellow-feathered broilers

The effects of supplementing broilers' diets with fermented cottonseed meal (FCSM) on the broilers' performance, apparent digestibility, carcass traits, and meat composition were studied. A total of 180 yellow-feathered chickens of 21 days old were randomly divided into three groups (six replicates of 10 broilers each): 1) a control group (Con), 2) a treatment group of FCSM by Candida tropicalis (Ct), and 3) a treatment group of FCSM by C. Tropicalis plus Saccharomyces cerevisiae (Ct-Sc). Results showed that FCSM supplementation improved the average daily gain and gain-to-feed ratio from the 43rd to 64th and the 21st to 64th day, respectively (P < 0.05). The dietary nutrient digestibility of dry matter, crude protein, and crude ash significantly increased (P < 0.05) with FCSM supplementation. The abdominal fat content was lower (P < 0.05) in Ct and Ct-Sc than in Con (21st to 42nd day). The crude protein content was higher in the thigh muscles of treatment groups and breast muscles of Ct, and the crude fat (ether extract) in the breast muscles of Ct-Sc was higher than in Con throughout the entire duration (P < 0.05). In conclusion, FCSM is beneficial for broilers as it positively affects their growth and digestibility in addition to altering their meat compositions.

Nutrient density and slaughter age have differential effects on carcase performance, muscle and meat quality in fast and slow growing broiler genotypes

1. A 2 × 2 factorial design was used to investigate the differences in carcase, muscle and meat characteristics between fast and slow growing genotypes fed on low nutrient (LND) or high nutrient diets (HND) at their respective slaughter ages. 2. The birds were randomly assigned to treatments with 5 replicates of 145 birds for Wens Yellow-Feathered Chicken (WYFC, 5·75 birds/m2) or 115 birds for White Recessive Rock Chicken (WRRC, 7·25 birds/m2), according to the commercial recommendations for the two breeds and were fed on HND or LND. Birds were slaughtered at 63 d and 105 d of age. 3. The results showed WRRC had higher carcase yield and meat yield than that of WYFC, lower fat content, higher moisture content and lower cooking loss. The meat from WRRC was less tender and contained lower levels of polyunsaturated fatty acids (PUFA). 4. Birds fed on HND had higher breast meat yield, myofiber area and protein content in the breast muscle and lower fat content than birds fed on LND. The thigh muscle of birds fed on HND had higher levels of PUFA. Age had a positive effect on carcase parameters, but a negative effect on pH, meat tenderness and cooking loss, and the two genotypes exhibited different responses to the influence of nutrient density and age. 5. Genotype and age had the largest effect on carcase performance and meat quality. LND benefited meat quality and WRRC had larger responses in meat yield and shear force when fed on HND.

Effect of fasting on energy metabolism and tenderizing enzymes in chicken breast muscle early postmortem

Pre-slaughter fasting is a very important practice in the meat industry. The present study was designed to investigate the effect of fasting on energy metabolism and tenderizing enzymes in chicken muscle early postmortem. A total of 30 Yellow-feathered chickens were deprived of feed for 0h, 12h and 24h before slaughter (n=10 each group). Breast muscles were removed and cut into 3 parts and stored at 0°C for 0h, 3h and 10h. Samples were used for analyses of zymography, cathepsins, pH, glycogen/ATP/ADP/AMP, hormones and ultrastructure. Fasting caused the accelerated depletion (p<0.05) of glycogen, ATP and ADP before or immediately after slaughter, but no difference existed in ATP at 3 and 10h (p>0.05). Fasting resulted in greater ultimate pH (p<0.05). Zymography indicated that fasting delayed the activation of μ/m-calpain (p<0.05), however, it accelerated the release of lysosomal enzymes (p<0.05). Fasting for 24h resulted in greater ultrastructural changes and plasma corticosterone levels than fasting for 12h and control groups. Therefore, fasting for no more than 12h is acceptable in practice.

Changes in relative organ weights and intestinal transporter gene expression in embryos from white Plymouth Rock and WENS Yellow Feather Chickens

This study was conducted to evaluate the embryonic development of broilers with different growth rates and correlate the differences between the amino acid transporter and peptide transporter gene expression patterns to the growth of the small intestine. The results showed that the body and yolk weights of the White Plymouth Rock (WPR) embryos were higher than those of the WENS Yellow Feather Chicken (WYFC) embryos although the relative embryonic body weights were inversely correlated. We studied nine organs and classified them into four clusters according to their changes in relative weight during the hatching process. The levels of gene expression of SLC7A9, SLC1A1 and SLC15A1 in the small intestine increased during embryo development and were affected by breed. Breed-specific differences in embryonic development were observed for SLC7A9, SLC1A1 and SLC15A1 gene expression. When represented as a function of SLC7A9, SLC1A1 or SLC15A1 gene expression, strong correlations were observed for the weight of small intestine. We conclude that WPR embryos have a higher absolute growth rate but a lower relative growth rate in comparison with WYFC embryos. Moreover, the expression levels of the SLC7A9, SLC1A1 or SLC15A1 genes can be used as indicators for the growth of the small intestine.

Effects of breed and dietary nutrient density on the growth performance, blood metabolite, and genes expression of target of rapamycin (TOR) signalling pathway of female broiler chickens

This study was conducted to compare the effects of exchanged diets with identical energy level on characteristics of slow-growing (WENs Yellow-Feathered Chicken, WYFC) and fast-growing (White Recessive Rock Chicken, WRRC) female chickens. A total of 1450 WYFC and 1150 WRRC 1-day-old female hatchlings were used. A high-nutrient-density (HND) diet and a low-nutrient-density (LND) diet were formulated for three phases. A completely randomized experimental design with a 2 × 2 factorial arrangement (diet and breed), each with five replicates of 145 and 115 birds, was applied. The results showed that WRRC had a higher body weight (BW), average daily feed intake and average daily gain than WYFC throughout the experiment (p<.05). WYFC that were provided with HND groups had a higher BW only in the starter and grower phases, whereas WRRC had a higher BW in the HND group than in LND groups throughout the experiment. The feed:gain ratio and protein efficiency ratio (PER) were better for WRRC in the starter and grower phases; however, these ratios were better for WYFC in the finisher period. The LND groups had a higher PER throughout the experiment for both breeds (p<0.05). The breast and leg muscle weights were higher for WRRC compared with WYFC during the grower and finisher phases (p<0.05). WRRC had a lower liver index but higher serum UA and alkaline phosphatase (ALP) concentrations than WYFC (p<0.05). No diet effect was observed on organ indices, muscle yields or blood responses. The gene expressions of Rheb, TOR, S6K1 and 4E-BP1 in gastrocnemius muscle were the highest in the WYFC-LND groups at 63 and 105 days (p<0.05). These findings suggested that different genotypes respond differently to changes in dietary nutrient density and that lower-nutrient-density diets are optimal for the long-term housing of broiler chickens.

Effects of transport stress on blood metabolism, glycolytic potential, and meat quality in meat-type yellow-feathered chickens

To investigate the effects of transport stress on blood metabolism, glycolytic potential, and meat quality in male Chinese Lingnan meat-type yellow-feathered chickens, three hundred sixty 72-d-old birds were randomly assigned to 1 of 5 treatments: unstressed control, 45-min (short-term) transport with 45-min (short-term) recovery, 45-min transport with 3-h (long-term) recovery, 3-h (long-term) transport with 45-min recovery, and 3-h transport with 3-h recovery. Each treatment consisted of 6 replicates with 12 birds each. All birds (except control group) were transported according to a designed protocol. Long-term transport decreased the plasma glucose level (P < 0.001), glycogen concentration in both breast (P = 0.023) and thigh (P = 0.012) muscles, and affected the size of IIb fibers in the tibialis anterior by decreasing the area (P = 0.031) and increasing the density (P = 0.046), drip loss (P = 0.045), and the a* (redness; P = 0.040) value in breast muscle. Long-term recovery after transport also decreased the plasma glucose level (P = 0.018) and showed a trend toward decreased breast glycogen concentration (P = 0.064). These results suggested that transport did not cause any noticeable changes in overall meat quality characteristics, although breast meat drip loss and meat color were affected. A long-term recovery from a period of feed and water deprivation also caused hypoglycemia and did not improve meat quality in Lingnan meat-type yellow-feathered chickens.

Effect of Dietary Conjugated Linoleic Acid (CLA) on Abdominal Fat Deposition in Yellow-feather Broiler Chickens and Its Possible Mechanism

A total of 60 one-day-old Yellow-feather broiler chickens were allotted into treatment and control groups. The treatment group was fed with the diet supplemented with 3% conjugated linoleic acid (CLA) for 48 d, while control group was fed with the diet supplemented with 3% rapeseed oil. Chickens were slaughtered in each group at the age of 49 d, and the blood and the abdominal adipose tissue were sampled. Serum cLeptin and serum cAdiponectin were measured by ELISA. The total RNA was extracted from adipose tissue to measure the abundance of the chicken growth hormone receptor (cGHR), insulin-like growth factor 1 (cIGF-1), insulin-like growth factor I receptor (cIGF-IR), peroxisome proliferator-activated receptor gamma (), cAdiponectin and cAdipoIR mRNA by RT-PCR using -actin as an internal standard. Results showed that the CLA decreased the abdominal fat index by 20.93% (p mRNA in abdominal adipose tissue by 24.74% (p0.05) in the relative abundance of cIGF-1, cIGF-IR, cAdiponectin, and cAdipoIR mRNA in abdominal adipose tissue. The data suggested that CLA inhibited abdominal fat deposition in broiler chicken may be determined by decreasing the GHR available for GH, and by inhibiting the differentiation of preadipocytes via down-regulation of , but independent of IGF and (or) GH-IGF pathway or adiponectin action.